Greasy Fork is available in English.
Duolingo - Speedier Timed Practice
Should work in all language courses on Duolingo, for both the global "strengthen skills" and individual skill "strengthen" sessions. Designed primarily to be used to make timed practice a bit speedier, but does also work in regular non-timed practice as well.
What this does: When you click the "Check" button after typing your answer, this userscript automatically clicks the "Continue" button straightaway. The answer result bar that you would've seen is copied over to the new question that loads, so that you can still glance at the answer correction if you were marked wrong. The "Check" and "Skip" buttons still work. However "Skip" just isn't visible as it is beneath the copied answer result bar, but people should be able to figure out where its replacement is easily enough. ^^
Downside: "Report" and "Discuss" buttons won't be usable at all. This userscript is purely for people who just want speed. Reporting stuff and reading sentence discussions isn't sensible in timed practice, as the timer will still tick down while doing these things.
It would be very complicated to make "Report" and "Discuss" buttons work when on the next question. I don't think it would be *impossible* and would be very cool if I got it working, but it's unlikely I'll get around to it.
Hope people find this userscript makes timed practice more enjoyable. ^^
(And, if you're doing the EN→JA or JA→EN courses, I recommend combining this with my Auto IME On-Off userscript.)
